21 SC Alternate Idea:
When I discovered I needed to replace my centerboard springs, the first step was to search this forum for ideas/instructions. I was happy to hear that the SC had an access port to greatly simplify this job. Then I opened to hull hatch, poked my head in and was greatly disappointed to see a solid bulkhead. What are the choices? Start cutting? From an earlier thread, I found the following:
The early Sport Cruiser had no access bulit in for spring replacement... an oversight. You need to cut an access in the bulkhead. You can install a port.
Director of Parts and Accessory Sales
Hobie Cat USA
Mine was a 1999, which I thought was near the end of the run, but I guess it qualified as an early model.
Anyway, I am not particularly fond of cutting holes in boats, especially with the risk of accidentally cutting into the centerboard trunk, so the following is how I accomplished the job without cutting, which also means without removing the upper attachment bolt. If you like carnival games more than cutting into your boat, this technique may be for you as well.
Disclaimer: I am not advocating straying from anything Hobie recommends. This is something that worked well for me and helped me keep from cutting into the boat. Maybe it will work for you as well, but use at your own risk.
Safety: As always, whenever working under something, make sure it is properly supported. No need to risk crushing injuries. Also, make sure to use eye protection, as this method could involve looking up at your work piece while hoping it comes down/out, which it will do, with force.
Now to the process. Most of it is described well in this thread, the manual available elsewhere on this site and in other threads, so I am only going to focus on the actual removal and installation of the springs themselves. This process is intended for the boat to be right side up whereas the Hobie instructions discuss flipping the boat over.
Remove the boards as described elsewhere. (may require lifting the boat and/or trailer)
A portion of the spring(s) is likely still attached to the upper attachment bolt and must be removed. To do this, bend a coat hanger into a hook shape like this, leave enough length on the free end to reach outside the hull and create a handle:
Insert hook all the way through the center of spring and hook it on the upper end near where it is attached to the bolt. It will look something like this, but you won't really be able to see it:
Now get yourself away from the line of action of the spring and give the hook a good firm pull. The upper end of the spring should unravel and separate from the attachment bolt. This will be a very firm pull, but I don't think there is risk of damage. The attachment bolt and surrounding fiberglass should be much stronger than the spring. Be careful as it may come out of the trunk with speed/force. Remove the second spring the same way.
To re-install with new springs, first modify the loop on the end of the new spring to facilitate installation. This will require you to open the loop slightly and push it off center slightly. The least modification the better, probably, but it should slip easily over the attachment bolt. I am not sure what size the bolt is, I just used a #2 Philips screw driver shaft as a gage. Here is what the spring should look like before and after the mod. Note that this is only needed on one end of the spring.
Next, create an installation tool to lift the spring into place:
The spring on the lifter will look like this:
Using the lifter, lift the spring into the centerboard trunk and hook it over the attachment bolt. Note: there is a spacer on the attachment bolt and 1 spring must be on each side of it. You will need to slide the spacer over toward the first spring to make room for the second. Hooking the second spring will likely be the hardest part of this process and will take a few tries. Note that an unsuccessful try results in the spring falling toward your face. Take the necessary safety precautions.
After the second spring is in place, complete the job by attaching the lower end of the springs and the pull rope (between springs) to the centerboard and reinstall the board as described elsewhere.
And the final step: congratulate yourself on completing a tough job without cutting any holes in an otherwise perfect boat.
I hope this helps someone out there.